A complete sentence consists of subject and:

In English grammar, a complete sentence is a fundamental unit of expression that conveys a complete thought. It must contain two essential components: a subject and a predicate.

• The subject is the noun or pronoun that performs the action or is described.
• The predicate is the part of the sentence that contains the verb and provides information about the subject, describing what the subject is doing or what is being said about it.

Therefore, a complete sentence consists of a subject and a predicate.

• Option A (Object) is a part of the predicate but not the entire second essential component.
• Option C (Clause) is a group of words containing a subject and a predicate, but 'predicate' specifically names the other essential part.
• Option D (Verb) is the core of the predicate, but the predicate includes more than just the verb.